000 AXNT20 KNHC 112350 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 11 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 38W S OF 18N MOVING W NEAR 15 KT. SATELLITE IMAGERY INDICATES THE WAVE COINCIDES WITH A BROAD AREA OF LOW LEVEL CYCLONIC TURNING AS NOTED IN THE 800-950 MB CLOUD DRIFT WINDS. DEEP CONVECTION IS ABSENT IN THE VICINITY OF THE WAVE AS IT IS SURROUNDED BY A SAHARAN AIR LAYER OF DUST... HOWEVER POSSIBLE ISOLATED SHOWERS ARE WITHIN 250 NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE EXTENDS FROM 20N71W TO 8N74W MOVING W NEAR 22 KT. THE WAVE IS MOVING BENEATH A BROAD UPPER TROUGH OVER THE CENTRAL CARIBBEAN THAT IS ENHANCING SCATTERED SHOWERS FROM 16N-23N BETWEEN 65W-73W...INCLUDING HISPANIOLA AND THE TURKS AND CAICOS ISLANDS. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N14W 8N22W 10N36W 6N40W 6N57W. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM SOUTH OF THE AXIS BETWEEN 12W-24W. ...DISCUSSION... GULF OF MEXICO... A LARGE UPPER HIGH OVER THE SRN PLAINS IS PROVIDING NELY FLOW AND ADVECTING DRY AIR SWD OVER THE NRN GULF...SUSTAINING A SURFACE RIDGE ANCHORED ACROSS THE SE CONUS AND NRN GULF WATERS ALONG 29N. DAYTIME INSTABILITY AND SEABREEZE CONVERGENCE IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS THE FLORIDA PENINSULA. A CUT-OFF UPPER LOW IS OVER THE YUCATAN PENINSULA NEAR 20N88W. INSTABILITY NEAR THE UPPER LOW AND A SURFACE TROUGH ACROSS THE FAR ERN BAY OF CAMPECHE IS GENERATING SCATTERED SHOWERS AND TSTMS S OF 22N BETWEEN 89W-92W. ALSO FARTHER N ACROSS THE CENTRAL GULF...SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM 24N-27N BETWEEN 87W-93W. THE WEAK RIDGE ACROSS THE NRN GULF WATERS WILL SHIFT S TO ACROSS THE CENTRAL GULF BY MON AND REMAIN THROUGH MIDWEEK. CARIBBEAN SEA... AN UPPER LOW CENTERED OVER THE NRN YUCATAN PENINSULA EXTENDS TROUGHING E-NE ACROSS CUBA AND INTO THE W ATLC. SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE NW CARIBBEAN AND CUBA N OF 18N BETWEEN 78W AND W BEYOND THE YUCATAN PENINSULA COAST. A SECOND UPPER LOW IS OVER ERN CUBA WITH AN UPPER TROUGH EXTENDING S ACROSS THE CENTRAL CARIBBEAN. MODERATE TO STRONG TRADE WINDS ARE ACROSS THE BASIN BETWEEN THE SUBTROPICAL SURFACE RIDGE OVER THE CENTRAL ATLC AND A TYPICAL BROAD TROUGH OVER NRN SOUTH AMERICA. THE STRONGEST FLOW WAS DEPICTED ON A 1515 UTC ASCAT PASS NEAR THE COAST OF COLOMBIA WITH WINDS AROUND 25 TO 30 KT. THESE WINDS WILL REMAIN STRONG OVER THE NEXT SEVERAL DAYS AS THE SUBTROPICAL RIDGE REMAINS ANCHORED IN THE CENTRAL ATLC. UPPER LEVEL DIFFLUENCE AND LOW LEVEL CONVERGENCE OVER THE SW CARIBBEAN IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 18N BETWEEN 80W-86W INCLUDING PORTIONS OF CENTRAL AMERICA. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ACROSS THE SW NORTH ATLC AND SUPPORTS A 1018 MB SURFACE LOW CENTERED NEAR 33N68W WITH A SURFACE TROUGH EXTENDING TO NEAR 30N70W. ANOTHER SURFACE TROUGH IS POSITIONED FROM 27N70W ACROSS THE SE BAHAMAS TO 22N76W AND IS GENERATING SCATTERER SHOWERS AND ISOLATED TSTMS WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH. FARTHER TO THE E...A THIRD IMPULSE OF ENERGY ANALYZED AS A SURFACE TROUGH EXTENDS FROM 27N64W TO 23N66W. SCATTERED SHOWERS COVER THE AREA FROM 23N-27N BETWEEN 63W-66W WITH THE SURFACE FEATURE AND THIS ACTIVITY IS AIDED BY UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER LEVEL RIDGE WITH AXIS ALONG 65W. THE REMAINDER OF THE CENTRAL AND ERN ATLC IS RATHER TRANQUIL E OF 60W WITH A LOW TO MIDDLE LEVEL DRY SAHARAN AIR LAYER EXTENDING OVER THE AREA S OF 28N TO 50W. $$ HUFFMAN